package com.hmdp.utils;

import cn.hutool.core.lang.UUID;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;

import java.util.Collections;
import java.util.concurrent.TimeUnit;


public class SimpleRedisLock implements ILock {

    private String name;
    private StringRedisTemplate stringRedisTemplate;

    public SimpleRedisLock(String name, StringRedisTemplate stringRedisTemplate) {
        this.name = name;
        this.stringRedisTemplate = stringRedisTemplate;
    }

    private static final String KEY_PREFIX = "lock:";
    private static final String ID_PREFIX = UUID.randomUUID().toString(true) + "-";

    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    static {
        UNLOCK_SCRIPT = new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        UNLOCK_SCRIPT.setResultType(Long.class);
    }

    /**
     * set lock thread1 NX EX 10
     */
    @Override
    public boolean tryLock(long timeoutSec) {
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        //获取锁
        Boolean success = stringRedisTemplate.opsForValue()
                .setIfAbsent(KEY_PREFIX + name, threadId + "", timeoutSec, TimeUnit.SECONDS);
        return Boolean.TRUE.equals(success);
    }

    /**
     * del key
     */
    @Override
    public void unlock() {
        //调用lua脚本实现redis操作的原子性
        /**
         * redis提供了lua脚本
         * 在一个脚本中编写多条redis指令，确保多条指令执行时的原子性
         */
        stringRedisTemplate.execute(
                UNLOCK_SCRIPT,
                Collections.singletonList(KEY_PREFIX + name),
                ID_PREFIX + Thread.currentThread().getId());
    }
    /*
    @Override
    public void unlock() {
        //首先获取当前线程的标识，
        String currentThreadId = ID_PREFIX + Thread.currentThread().getId();
        //获取锁中的标识
        String IdInLock = stringRedisTemplate.opsForValue().get(KEY_PREFIX + name);
        //是否是自己的持有的锁
        if (currentThreadId.equals(IdInLock)) {
            //释放锁
            stringRedisTemplate.delete(KEY_PREFIX + name);
        }
    }*/
}
